For a supraclavicular brachial plexus block, after the ultrasound probe is placed in the transverse plane immediately proximal to the clavicle, what statement is true? A. Clockwise rotation can help visualize the sheath containing the plexus. B. Color Doppler should be routinely used prior to needle insertion. C. Tilting the transducer caudally can help to obtain a cross-sectional view of the subclavian artery. D. All three statements are true.